Code finding key



*Sepi-f 24, 1935.

R. SIMON 2,015,322

CODE FINDING KEY Filed July lO, 1954 INVENTOR eubezz 752mm?,

S ATTORNEYS Patented Sept. Z4, 1935 UNITED STATES PATENT OFFICE 1 Claim.

It has been the practice to provide a complete series of code finding keys for the locks of each manufacturer, the number of such keys necessarily equalling the number of combinations of I notches and notch depths employed by such manufacturer. Thus, for example, if, a manufacturer provides in his series, keys having five notches varying in depths from one to five units then the possible number of combinations equals five raised 10 to the fth power. In such instances a key maker would require that number of code finding keys in order to determine the code number of the key for a particular lock, the uses of such code finding keys being entirely familiar to those skilled.

15 The object of the present invention is to provide an improved code finding key which will make it possible to reduce the number of code finding keys necessary to determine the code number of a key for a particular lock. Taking the example 20 set forth above, by way of illustration, where present practice requires a total number of code finding keys equal to the number of notches raised to that power equal to the number of notch depths employed, the present invention makes it possible 25 to reduce that number of code finding keys to a number equal to the number of, notches, minus one, raised to that power equal to the number of different notch depths. Statednumerically, while present practice would require 3125 different code finding keys where five notches are employed with ve different depths, the present invention makes it possible for 1024 different code finding keys to serve the purpose for such a .series of locks. Such a result follows in accordance with 35 the invention regardless of the number of notches and number of different notch depths. v

In accordance with the invention a code finding key is provided which has a number of notches for coaction with the tumblers equal to the numi ber of tumblers, minus one, and a cam surface to actuate the remaining tumbler. The notches thus provided in the improved code finding key are of such width at their bases (considered longitudinally of the shank of the key) as to permit free 'l5 longitudinal movement of the key without moving the respective tumblers, for a distance suf.- ficient to permit the said cam to move the said remaining tumbler throughout its effective locking range. Thus, having'the correct code finding 50 key for all of the tumblers save one the remaining tumbler, by proper manipulation of the key, can be cammed out of locking position and the cylinder of the lock (if it be a cylinder lock) revolved freely. With this determination the re- 55 quired key can be readily formed from a blank Vpermit the cylinder to revolve.

since the code number is known for al1 of the notches save one and the depth of that notch can be determined readily by trial.

The invention will be more fully described in connection with the embodiment illustrated in the 5 accompanying drawing, wherein:

Figure l is a view in section showing somewhat conventionally a cylinder lock and its tumblers, mounted within a barrel, and in side elevation, a code finding key embodying the improvements, in its relation to the tumblers.

FigureZ is a view in side elevation of a code finding key embodying the invention but of slightly modified form.

The improvements have been illustrated and l5 will be described with reference to cylinder locks.

A code finding key is used, as the name implies,

to determine the code numbers of a key to fit a particular lock. According to the make of. lock it is known, of course, how many tumblers are provided so that the problem in fitting a key to the lock is to determine the notch depths for the respective tumblers. There has been illustrated in Figure l, in conventional form, a barrel a of a lock having mounted revolubly therein a cylinder b in which are carried five tumblers c, c', c2, c3 and c4, these tumblers being movable by the proper key into such relation to the barrel as to In accordance with present day practice a key maker is provided with a series of code finding keys which he must use by trial and error until he locates the right one to free the tumblers from the barrel. In the case illustrated, for example, there are five tumblers and so the desired key would have five notches. It may be assumed that these several notches have ve different depths. Accordingly,

a complete series of code finding keys to ascertain the correct code number would equal in number ve raised to the fifth power. Obviously, the number of such code finding keys required is an important practical consideration both as regards initial expense and facility in determining the correct combination. In accordance with the present invention, under the example given, the number of code finding keys required would be reduced to four raised to the fifth power.

Referring now to Figure l it will be seen that the improved code finding key d has four notches d', d2, d3, d4, the number of notches being one 50 less than the number of tumblers. Each of these notches at its base is of greater width than the thickness or diameter of the tumblers c, c', c2, c3, respectively, with which they coact. This addition-a1 width permits the key d to be moved freely longitudinally within the limits of the notches without actuation of the several tumblers seated therein. Having selected a code finding key with the proper notches d', d2, d3, d4, for coaction with the respective tumblers c, c', c2, c3, the remaining tumbler c4 must be retracted from the barrel to permit the cylinder to turn. This is accomplished by forming at the end of the key a cam surface d5 which coacts with the tumbler c4 upon longitudinal movement of the key d. By proper feel the cam d5 is caused to move the tumbler c4 into proper relation to the barrel to permit the cylinder to revolve. Having accomplished this the operator knows that the particular code fin-ding key employed has the first four notches of proper` depth. He thereupon files a blank with four notches of the depth equal to the respective notches d', d2, d3, d4. The depth of the fifth notch he thereupon determines by trial and error filing it to the successive possible notch depths until he finds the tumbler c4 in proper relation to the barrel to permit the cylinder to revolve.

In Figure 2 is shown a slight modiiication of an improved code iinding key D. In this embodiment the notches of predetermined depth are illustrated at D2, D3, D4 and D5, the last notch D5 being in the position of the fifth notch of the key at the end of the shank. These several notches are adapted to coact in normal manner with the respective tumblers illustrated in Figure 1 at c', c2, c3, c4. When using the code key illustrated in Figure 2 the iifth tumbler c is engaged for actuation by a cam surface formed in a narrow notch D', this notch being of maximum depth for the particular series of keys, this maximum depth in the example assumed being five units. It will be noted that in this embodiment the key notches D2, D3, D4, D5, are of greater width than the tumblers, as explained heretofore, so that the key D may be moved longitudinally to cause the cam surface of the notch D to coact with the remaining tumbler c so as to bring it into such relation to the barrel that the cylinder may be revolved. It will be observed that the notch D is not at its base of greater width than the tumbler c. The use of the code finding key D illustrated in Figure 2 is the same as that .described with reference to the key d in Figure 1. Having the correct notch depths for the notches D2, D3, D4, D5 manipulation of the key longitudinally will enable the remaining tumbler c to be brought into proper relation by the action of the cam surface of the notch D whereupon the cylinder may be revolved. Having thus verified the correct notch depths for four of the notches the correct depth of the remaining notch for coaction with the tumbler c may be found by trial and error in ling the key blank.

From the description given it will be apparent that the key maker in using the improved code finding key is concerned only with locating the key which will correctly actuate four of the tumblers and when he has located the correct code finding key his determination will be verified by camming the ith tumbler into proper relation to the barrel thereby enabling the cylinder to be revolved. Thus the number of code finding keys that must be carried in stock for locks of a particular make has been very substantially reduced as pointed out hereinbeiore, thedifculty of locating the proper code iinding key for the particular lock to be fitted is greatly reduced and the initial investment has been correspondingly reduced.

It will be evident to one skilled in the art that modifications embodying the same principle may be made to meet the requirements of locks and keys of diierent characters but all such modications are to be deemedA within the scope of the :lo invention if they embody the principle dened by the appended claim.

What I cl-aim is:

A code nding key for the purpose specified having a plurality of notches for coaction with 3., the tumblers of a lock, the number of said notches being less by one than the number of said tumblers and the notches being twice as wide as said tumblers to permit longitudinal movement of the key, and a cam c-arried by the key and formed to engage the remaining tumbler initially when the notches of the key first release the tumblers in the inward motion of the key into the lock, the cam being further formed to move the remaining tumbler to a releasing position upon further lon- 4,5 gitudinal movement of the key equal to the width of a tumbler.

REUBEN SIMON 

